Production of high frequency waves in a liquid medium



F. G. FIRTH July 10-, 1951 PRODUCTION OF HIGH-FREQUENCY WAVES IN ALIQUID MEDIUM Filed May 14, 1948 a I i i i i i n I l INVENTOR WATTORNEYS Fumcbi Gen Y @mfiwmafm @WM Patented July 10, 1951 PRODUCTIONOF HIGH FREQUENCY WAVES IN A LIQUID MEDIUM Francis George Firth, NewYork, N. Y.

Application May 14, 1948, Serial No. 27,093 In Australia March 24, 19486 Claims. (Cl. 116-137 This invention relates tlxthe production of highfrequency waves in a. liquid medium, and has for its object theprovision of a novel device or system for setting up within a liquidmedium waves or vibrations of high frequency.

In a number of commercial fields the application of intense agitationtechniques has proven to be of great value. These fields include amongstothers chemical manufacturing, emulsiflcation of fluids, mixing, textilecleaning and sterilization. The amount of energy that can be employedwith mechanical mixing under normal conditions is very limited, and theagitation is necessarily localised around the impeller or like agitatingelement in the treating vessel.

The amount of energy that can be developed in such applications can beincreased considerably by suitable techniques that employ frequencies ofagitations covering the sound spectrum up to very high frequencies. Therange of frequencies might be expected to cover, say, 50 cycles persecond to 1 mega-cycle per second. For instance, one may refer to thesound spectrum covering frequencies up to say 15,000 cycles, and theultrasonic range from 15,000 cycles per second upwards.

The present invention contemplates an hydraulic system or device fortransforming the energy of a high velocity fluid jet into anintermittent high frequency form 'capable of performing work, and, aswill become apparent hereinafter, a system or device which is practical,relatively simple, safe to use, capable of large power inputs, of highefliciency, and suitable for commercial applications involving liquid,or liquidgaseous phases.

In accordance with the invention I utilize a high-energy, high velocityliquid jet and arrange for a controlled small volume of air or anappropriate gas to be admitted into the liquid jet which is directedagainst a re-action member capable of vibrating at high frequency. Theair or gas, being compressible, introduces the factor of intermittencyinto the otherwise constant pressure of the liquid jet. The liquidimpinging on the member causes it to extend, while the entrained gaspermits it to recover. Thus, the combined effect of the jet of liquidand entrained gas is to vibrate the member at high frequency, and there-action member transmits the high frequency waves to the body ofliquid to be treated.

The invention will be more readily understood from the followingdescription, relating to certain typical embodiments, aided by referenceto the accompanying diagrammatic drawings. It is, however, to beunderstood that the following description and the drawings are merely byway of example and that various modifications, refinements and/oradditionsas would readily occur to those versed in the art after readingthis 2 specification, may be incorporated without departing from thespirit and scope of the invention.

In Figure 1 a driven hydraulic pump l is shown connected at the outputside to a pipe 2 that 4 of the pipe 2 is located concentrically with theapex A of a flexible diaphragm 5. The diaphragm may advantageously be ofthe shape of a right cone with a base 3,31. The diaphragm is connectedat its perimeter with, a container vessel 0.

Spaced radially and circumferentially around the apex point A, but belowit, are a plurality of holes I in the diaphragm which permit freepassage of fluids, gases and solids from the interior of the diaphragmto the container vessel. A relatively small diameter tube 8 is connectedto the interior of the pipe 2 at the low pressure point of the Venturiconstriction, in much the same manner as a water aspirator, which is awell-known vacuum device, for withdrawing gases or liquids from a'system.

The action of the device of Figure 1 is as follows:

The driven hydraulic pump I is supplied with a liquid through an inletpipe 9, and the liquid is forced at a high pressure through the outletpipe 2 past the Venturi constriction 3 to the outlet nozzle 4. Theresulting high pressure liquid stream will impinge on the diaphragm 5 atthe apex A. The diaphragm is supported rigidly at the base 331, andsince it is composed of a suitable flexible material, it will tend toextend itself away from the direction of the force from the jet.

Air is drawn through a throttling valve into the tube 8, and admitted inregulated volume to the liquid flowing through the outlet pipe 2, andwill appear as intermittent bubbles of air in the liquid stream. Thiswill cause an effect of intermittency to appear in the force of theliquid jet, and the diaphragm will recover intermittently to a lessstressed condition.

Thus, the diaphragm will tend to vibrate at a rate that will bedependent on a number of factors including:

(a) The natural period of vibration of the diaphragm system,

(b) The liquid jet pressure,

(c) The amount of air or gas admitted to the fluid moving system,

(d) The geometry of the system.

In accordance with the invention, these factors are adjusted to causethe diaphragm to vibrate at high frequency, which throughout thisspecification and the appended claims means a frequency of not less than50 cycles per second. Any or all of these factors can be changed at willwith suitable apparatus and the amount of hydraulic energy that it ispossible to dissipate is very large. This dissipation of energy will bepartly used in moving the diaphragm ABBi.

Thus, any body of liquid held in the container 6.

above the diaphragm will be subjected to vibrations due to the movementof the diaphragm.

It is to be understood that the foregoing embodiment of the invention isonly one method of application. The holes I are unnecessary for theoperation of the device, if a sealed oil. container vessel is required.Furthermore, the hydraulic liquid can be recirculated by collecting theliquid after it falls from the inner surface of the diaphragm, and byintroducing it through inlet pipe 9.

Instead of air being introduced through the tube 8, other gases may beused, as for example, an inert gas suciras argon, a gas for carbonationof water such as carbon dioxide, or any other desired gas.

If it is required that two materials be intimate- 1y mixed, another sidetube may be connected to the Venturi constriction, at a place close tothe gas tube 8, in such a way that another liquid, gas or solid can bemixed with the pumped liquid. Such an arrangement might be desirable ina chemical precipitation reaction for example, or in connection with theemuisification or dispersion in a liquid medium.

It is to be clearly understood that the diaphragm itself does notnecessarily have to be a flexible element in the moving system. Thediaphragm can be rigid and supported at the base 13,131 by a flexiblemember, such as a ring R (Figure 2) between the base and main rigidsupport.

According to another modification, the diaphragm may be supported at thebase in a rigid fashion by the container 6 which is in itself rigidlysupported at the end away from the base, and a flexible section let intoit, as for example, a ciroumferentially corrugated zone C (Figure 3)somewhere between the support and the base.

The diaphragm does not necessarily have to be of the shape of a rightcone, but can be of other appropriate geometric shapes, or of a planarsurface, without departing from the spirit of the invention.

An example of the application of a device as before described to apractical usage may be as follows:

Presently available commercial and domestic machines for washing orcleaning fabrics use methods of agitation of the cleaning fluid of amechanical nature, so that the fluid is moved through the fabrics bymeans of a mechanically operated paddle mechanism, or by moving thefabrics through the fluid by a rotating drum. Although such mechanismsare to a certain extent eifective they are in fact of very lowefllciency due primarily to the waste of mechanical power which movesboth the fluid and fabrics simultaneously.

By placing the fabrics in a vessel such as the container 6 in theaforementioned devices and covering them with a washing or cleaningliquid, the diaphragm ABBl can be caused to move at a high frequency byoperating the hydraulic pump and admitting a controlled volume ofatmospheric air to the tube 8.

The liquid in the container can be recirculated through the pump andreturned to the system through holes in the diaphragm. For this purposethe outlet pipe 2 should be sealed within the base of the diaphragmsystem, and the air pipe 8 be brought out to a point where air isavailable.

Thus, the movement of the diaphragm will cause the body of liquid aboveit to move at a high rate of speed through the fabrics, causing acleaning action without the abrasion to the fabrics that is inevitablewith a conventional washing machine. The efliciency of the process isalso enhanced by the higher circulating frequencies provided, and bybetter power conversion.

I claim:

1. A device for producing high frequency vibrations in a liquid mediumcomprising a container for the medium, a reaction member capable ofvibrating at high frequency positioned within the container, means fordirecting against said reaction member a high velocity jet of liquid,and means for introducing a gas into said liquid jet.

2. A device for producing high frequency vibrations in a liquid mediumcomprising a container for the medium, a reaction member capable ofvibrating at high frequency positioned within the container, and meansfor vibrating said reaction member at high frequency by directingagainst it a high velocity jet of liquid and compressible gas.

3. A device for producing high frequency vibrations in a liquid mediumcomprising a container for the medium, a reaction member capable ofvibration positioned within the container, means for directing a highvelocity liquid jet against one side of said member, and means forintroducing intermittent bubbles of gas into the liquid jet whereby thereaction member is caused to vibrate at high frequency as the liquid jetand entrained gas bubbles impinge against it.

4. A device for producing high frequency vibrations in a liquid mediumcomprising a container for the medium, a diaphragm positioned within thecontainer and capable of vibrating at high frequency, and means fordirecting against said diaphragm a jet of incompressible liquidcontaining a compressible gas.

5. A device according to claim 4 in which the diaphragm is a conicalmember of flexible material.

6. A device according to claim 4 in which the diaphragm is a rigidconical member flexibly supported within the container.

FRANCIS GEORGE FIRTH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 899,820 Abbott, Jr Sept. 29, 19081,445,096 McKerahan Feb. 13, 1923 1,475,385 Hecht et al Nov. 27, 1923

